Now this is going to be really tough since I remember very little about the novel, but maybe...
The novel is something between political satire and psychological/psychedelic/psychiatric thriller, similar in spirit to movies like The Ruling Class or rather Todo Modo. The reason I seek analogies in movies rather than in literature is that (a) the style was so vivid and picturesque that I still have the impression of having actually seen it as a movie rather than having read it in text and (b) I can't really think of any novel with similar developments.
The whole plot took place in some secret underground offices, where government officials were secretly meeting for various hidden activities ranging from deciding state matters of utter importance to various secret forms of entertainment. Actually that secret place was the main character, and maybe even its name was present in the title, although again maybe not. The characters, mostly ministers, parliament members, maybe some occasional very high profile prostitutes, were behaving extravagantly, much attention was given to their unusual but strict dress-code - some satin-like black cloaks, ties, ...
The plot was outstandingly dynamic, gradually becoming more and more bizarre and paranoid, towards the end feverishly so, there were astonishing revelations which were never confirmed and might actually be just results of serious mental disorder of either storyteller or of the very universe. This was the main characteristic of the novel for me, I've never seen such incredible acceleration of the plot and such deep intermingling of reality with insane delusions.
I did read it around early eighties, or maybe mid-eighties, in Russian translation, in the Soviet magazine Иностранная Литература (Foreign Literature).
The author was either Italian or English/American, I don't remember for sure.
I'm afraid that's all I can remember. Maybe asking this question here stimulates my memory and I can come up with more details, in that case of course I will add them here.